undici vulnerable to cross-user information disclosure via whitespace around equals in Cache-Control directives

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

5.9 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS

• CVE-2026-14643: 0.40% estimated exploitation activity in the next 30 days; percentile 33.82 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact Undici's cache interceptor mishandles optional whitespace (OWS) placed around the = of a qualified no-cache or private Cache-Control directive, such as no-cache ="authorization" (OWS before =) or no-cache= "authorization" (OWS after =). The parser either drops the directive entirely or stores a field name with literal quote characters, so the downstream cache decisions do not recognize the qualification and the response is stored. In shared-cache mode, this allows a response containing one user's authenticated data to be served from cache to a subsequent caller, including an unauthenticated caller, when both requests resolve to the same cache key. The impact class is identical to CVE-2026-9678 (GHSA-pr7r-676h-xcf6); this advisory covers the whitespace-around-= bypass that the earlier fix did not normalize. Affected applications are those that explicitly enable the cache interceptor (interceptors.cache()) in shared mode, forward Authorization headers upstream, and receive…

Published by the source

3 Aug 2026, 19:32 UTC

Last modified by the source

3 Aug 2026, 19:32 UTC

Source last checked

26 Oct 2026, 13:00 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-jr45-8vmc-qm54

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-14643

Advisory: undici vulnerable to cross-user information disclosure via whitespace around equals in Cache-Control directives
IDs: CVE-2026-14643, GHSA-jr45-8vmc-qm54
Record: https://patchnext.com/advisories/cve-2026-14643 (revision 1, source checked 26 Oct 2026, 13:00 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: undici 8.9.0, 7.29.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm undici: affected >= 7.0.0, < 7.29.0; >= 8.0.0, < 8.9.0; fixed in 8.9.0, 7.29.0

## Suggested inspection (read-only)
- `npm ls undici --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on undici.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-jr45-8vmc-qm54 (GitHub-reviewed advisory GHSA-jr45-8vmc-qm54 lists affected ranges: npm undici >=7.0.0 =8.0.0 <8.9.0)

Commands are suggestions: review each one before running it.